Null properties are dropped during marshalling/unmarshalling with JSONIX - jsonix

Question

I noticed that in my conversion from JSON to XML, if one of my JSON objects is null, the object is absent from the XML, for example
JSON
{
"name": {
"namespaceURI": "",
"localPart": "myApp",
"prefix": "",
"key": "myApp",
"string": "myApp"
},
"value": {
"TYPE_NAME": "generated.MyApp",
"inputData": [{
"TYPE_NAME": "generated.MyApp.InputData",
"dataType": "text",
"mandatory": false,
"length": 25,
"valid": true,
"value":null
}]
}
}
Convert to XML output (marshalString)
var context2 = new j.Context([generated2]);
var marshaller2 = context2.createMarshaller();
var objectAsXMLString2 = marshaller2.marshalString(template2);
<myApp>
<inputData>
<dataType>text</dataType>
<mandatory>false</mandatory>
<length>25</length>
<valid>true</valid>
</inputData>
</myApp>
Then converting back again to JSON (unmarshalString)
var unmarshaller2 = context2.createUnmarshaller();
var resultJSON2 = unmarshaller2.unmarshalString(objectAsXMLString2 );
{
"name": {
"namespaceURI": "",
"localPart": "myApp",
"prefix": "",
"key": "myApp",
"string": "myApp"
},
"value": {
"TYPE_NAME": "generated.MyApp",
"inputData": [{
"TYPE_NAME": "generated.MyApp.InputData",
"dataType": "text",
"mandatory": false,
"length": 25,
"valid": true
}]
}
}
So as you see, there is loss of information. When the complete cycle of conversion occurs, JSON -> XML -> back to JSON, some properties are not preserved. Anything that is null gets dropped - in this case it is the property 'value'. This is a problem for downstream applications that are expecting certain properties to be present on an object.
My XML schema that was used to generate the jsonix mapping object looks like this
<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="myApp">
<xs:complexType>
<xs:sequence>
<xs:element name="inputData" maxOccurs="unbounded" minOccurs="0">
<xs:complexType>
<xs:sequence >
<xs:element type="xs:string" name="dataType"/>
<xs:element type="xs:boolean" name="mandatory"/>
<xs:element type="xs:short" name="length"/>
<xs:element type="xs:string" name="elementId"/>
<xs:element type="xs:string" name="formId"/>
<xs:element type="xs:anySimpleType" name="value" />
<xs:element type="xs:boolean" name="valid"/>
<xs:element type="xs:short" name="precision"/>
<xs:element type="xs:short" name="scale"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
And generated mapping using jsonix-schema-compiler is
var generated_Module_Factory = function () {
var generated = {
name: 'generated',
typeInfos: [{
localName: 'MyApp',
typeName: null,
propertyInfos: [{
name: 'inputData',
minOccurs: 0,
collection: true,
elementName: {
localPart: 'inputData'
},
typeInfo: '.MyApp.InputData'
}]
}, {
localName: 'MyApp.InputData',
typeName: null,
propertyInfos: [{
name: 'dataType',
required: true,
elementName: {
localPart: 'dataType'
}
}, {
name: 'mandatory',
required: true,
elementName: {
localPart: 'mandatory'
},
typeInfo: 'Boolean'
}, {
name: 'length',
required: true,
elementName: {
localPart: 'length'
},
typeInfo: 'Short'
}, {
name: 'elementId',
required: true,
elementName: {
localPart: 'elementId'
}
}, {
name: 'formId',
required: true,
elementName: {
localPart: 'formId'
}
}, {
name: 'value',
required: true,
elementName: {
localPart: 'value'
},
typeInfo: 'AnySimpleType'
}, {
name: 'valid',
required: true,
elementName: {
localPart: 'valid'
},
typeInfo: 'Boolean'
}, {
name: 'precision',
required: true,
elementName: {
localPart: 'precision'
},
typeInfo: 'Short'
}, {
name: 'scale',
required: true,
elementName: {
localPart: 'scale'
},
typeInfo: 'Short'
}]
}],
elementInfos: [{
typeInfo: '.MyApp',
elementName: {
localPart: 'myApp'
}
}]
};
return {
generated: generated
};
};
if (typeof define === 'function' && define.amd) {
define([], generated_Module_Factory);
}
else {
var generated_Module = generated_Module_Factory();
if (typeof module !== 'undefined' && module.exports) {
module.exports.generated = generated_Module.generated;
}
else {
var generated = generated_Module.generated;
}
}
Is there a way to preserve all properties during the conversion, even if they are null?

Answer 1

Not at the moment.
I think what you're looking for is support for nillable elements as you probably want to distinguish null vs. absent property vs. property with the empty string as value.
Jsonix does not support nillable elements at the moment.